Reagent and method for decomposing halogenated organic compounds

ABSTRACT

A reagent, comprising the product of the reaction of an alkali metal with a polyglycol or a polyglycol monoalkyl ether and oxygen, effects complete decomposition of halogenated organic compounds, such as polychlorinated biphenyls (PCBs), when mixed therewith in the presence of oxygen.

This application is a continuation-in-part of U.S. patent applicationSer. No. 142,865, filed Apr. 21, 1980, in the names of Louis L.Pytlewski, Kenneth Krevitz and Arthur B. Smith.

BACKGROUND OF THE INVENTION

The present invention relates generally to a composition of matter andto the use of said composition in a method for decomposing hazardoushalogen-containing organic compounds, such as polychlorinated biphenyls.

The potential hazard to public health and the environment posed by theindiscriminate disposal of a variety of synthetic halogen-containingorganic chemicals is well known. Compounds such as polychlorinatedbiphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT),decachlorooctahydro-1,3,4-metheno-2H-cyclobuta-[c,d]-pentalen-2-one(Kepone®), and 2,4,5-trichlorophenoxyacetic acid, (2,4,5-T), althoughhaving demonstrated utility, have been found in recent years to bepersistent environmental poisons, and, therefore, require a safe andeffective means of disposal.

The difficulty encountered in attempting to dispose of halogenatedorganic compounds is due in large measure to the highly stable nature ofthe carbon-halogen bonds present therein. The bond energy of acarbon-chlorine bond, for example, is on the order of eighty-fourkcal./mole. These compounds are not only resistant to biodegradation,they cannot be degraded in a practical and effective manner by any ofthe well-known chemical decomposition methods. Thus, although chemicaldecomposition of halogen-containing organic compounds, including PCBs,has been reported, the methods employed, such as chlorolysis, catalyicdehydrohalogenation, molten salt reactions, ozone reactions, and alkalimetal reduction, possess one or more significant limitations. Forexample, these prior art methods typically require expensive reagents,inert atmospheres, extensive temperature control, complex apparatus,substantial energy consumption, and the like. The principal problem withthese methods is that they achieve incomplete dehalogenation. Theimpracticability of the aforementioned prior art disposal methods isevidenced by the fact that none has gained widespread acceptance bygovernment or industry.

Incineration has also been employed as a means for disposal of hazardouschemicals but it too has certain notable drawbacks. In the first place,it requires substantial energy consumption. Hence, the expense involvedin this method of disposal will probably steadily increase. Secondly,incineration requires the use of complex equipment to remove corrosiveand/or toxic substances from the incinerator effluent. Thus, the expenseof constructing an incineration disposal facility makes it uneconomicalfor those having a hazardous chemical waste disposal problem who mightadvantageously employ a practical disposal system. Thirdly, the residualash formed during incineration may be toxic and present a furtherdisposal problem.

Only a few incineration facilities are currently in operation, and someof these are in remote locations, adding excessively high transportationcosts to the cost of disposal in many cases.

PCBs pose a particularly serious disposal problem. Once widely used asdielectric fluid additives in electrical equipment such as transformersand capacitors because of their excellent insulating properties, the useof PCBs were banned recently by the United States EnvironmentalProtection Agency (E.P.A.) due to their cumulative storage in humanfatty tissue and reports of extremely high toxicity. In connection withthe ban, the E.P.A. has promulgated a rule whereby the available meansof effective decomposition of extant PCBS and PCB-contaminatedsubstances is limited to incineration. However, incineration ofPCB-contaminated materials in accordance with E.P.A.-approved proceduresis decidedly wasteful since potentially recyclable materials, such asdielectric and hydraulic fluids, which may contain a relatively smallamount of PCBs are destroyed in the process. To avoid such waste, it hasbeen proposed to treat recyclable materials contaminated by PCBs with anabsorbent, e.g., by passing the material through a bed of activatedcharcoal or a resin to selectively remove the PCBs from said material.Although PCBs are physically removed from the recyclable material inthis manner, the disposal of absorbed PCBs still remains a problem.

Aside from the PCB disposal problem, there are significant quantities ofother waste or excess halogen-containing organic chemicals presentlybeing held in storage by manufacturers, processors or consumers, whichchemicals must be disposed of eventually in an environmentallyacceptable manner. Viewed realistically, storage of toxic chemicals canonly be considered a stop-gap measure while efforts to develop a safe,practical and effective process for their disposal continue. Storagecapacity is finite, whereas the amount of hazardous chemical substancesgenerated by industry is estimated to increase by about three percentannually.

It is apparent that a need exists for an effective and efficient processfor the decomposition of halogenated organic compounds, and preferablyone that is capable of (1) scavenging the hazardous substances frommaterials contaminated therewith, thus permitting reuse of saidmaterials, and (2) converting the hazardous substances to usefulproducts.

SUMMARY OF THE INVENTION

The aforementioned deficiencies of the prior art methods for disposingof halogenated organic compounds have been overcome in accordance withthe present invention wherein a halogenated organic compound isdecomposed by the steps of reacting an alkali metal, a suitable liquidreactant, such as a polyglycol or a polyglycol monoalkyl ether, andoxygen to form a decomposition reagent, and adding a halogenatedcompound, or mixture of halogenated compounds, to the decompositionreagent in the presence of oxygen to achieve decomposition thereof.

The present invention is particularly useful for the decomposition ofchlorinated organic compounds and results in complete and rapid cleavageof the carbon-chlorine bond. At elevated temperatures, thedehalogenation reaction goes to completion in less than 5 minutes.Moreover, the reagents used in carrying out the method are relativelyinexpensive and only relatively unsophisticated equipment is required.Both of these factors are significant from the standpoint of applicationof the method on a commercial scale.

Aside from providing a practical and effective means for the disposal ofhalogenated organic compounds that are uncontaminated with othersubstances, e.g., "neat" PCBs, the present invention makes it possibleto "scavenge", from otherwise useful materials, halogenated organiccompounds that are dissolved in relatively small amounts in thosematerials. For example, the present invention may be used to removechlorine from PCB-contaminated dielectric fluids. Further, the presentinvention is at once capable of decomposing halogenated organiccompounds and producing useful products which are readily recoverablefrom the reaction medium.

DESCRIPTION OF THE INVENTION

In accordance with the present invention, it has been discovered thatthe products of the reaction of molten alkali metals with certain liquidreactants, such as polyglycols or polyglycol monoalkyl ethers, andoxygen provide reagents capable of decomposing a host of halogenatedorganic compounds. When halogenated organic compounds, such as PCBs, areadded to this reagent in the presence of oxygen, dehalogenation occursquickly and completely.

As a practical matter, because of handling problems the alkali metalsparticularly suitable for practicing the present invention are sodium,lithium and potassium or the amalgams of these metals. Of these, sodiumis the preferred metal due to its high reactivity and relatively lowcost.

The liquid reactants that may be utilized in carrying out the presentinvention, have the general formula ##STR1## wherein R is hydrogen orlower-alkyl, R₁ and R₂ are the same or different and are selected fromthe group consisting of hydrogen, unsubstituted or substituted loweralkyl, unsubstituted or substituted cycloalkyl having from 5 to 8 carbonatoms, and unsubstituted or substituted aryl, n has a value from about 2to about 400, and x has a value of at least 2, which includespolyglycols and polyglycol monoalkyl ethers. The lower alkyl radical inthe foregoing formula may be methyl, ethyl, propyl, butyl, isobutyl,etc. The cycloalkyl radical may be cyclopentyl, cyclohexyl, cycloheptylan cyclooctyl. The aryl radical may be phenyl, benzyl, biphenyl,naphthyl, etc. The substituents on the R₁ and R₂ radicals include, butare not limited to, lower-alkyl, e.g. methyl, ethyl, propyl, butyl,isobutyl etc.; halo, e.g., chloro, bromo; nitro; sulfato; carboxyl;amino; mono- and di-lower-alkylamino, e.g. methylamino, ethylamino,dimethylamino, methylethylamino; amido; hydroxy, lower alkoxy, e.g.methoxy, ethoxy, etc.

Suitable liquid reactants falling within the above formula includediethylene glycol, diethylene glycol monomethyl ether, polyetherglycols, such as polyethylene glycols, polypropylene glycols, andpolybutylene glycol and related long chain glycol monoalkyl ethers. Thepreferred liquid reactants are those of the above general formulawherein R₁ and R₂ are hydrogen and x is 2. Particularly preferred arepolymers of polyethylene glycol having the formula HO--CH₂ --CH₂--O--_(n) H wherein n may have a value between about 2 and about 400.These polymers have an average molecular weight range from about 100 toabout 20,000. Neither low volatility, non-polar liquids, nor glycolicliquids in which both terminal hydroxyl groups are alkylated has beenfound to produce the desired decomposition.

The term "polyglycols", as used herein, is intended to signify polymersof dihydric alcohols.

In preparing the decomposition reagent, the alkali metal and liquidreactant are mixed together, preferably with stirring. The mixture maybe heated to accelerate the rate of reaction of the metal with theliquid. The extent of heating required will vary depending on theparticular metal and liquid used. In the case of a decomposition reagentformed from sodium and a polyethylene glycol having an average molecularweight of 400, for example, heating of the mixture to a temperature inthe range of about 50° C. to about 80° C. gives a satisfactory reactionrate. Upon heating, the reaction becomes exothermic and the temperatureof the reaction mixture rises to near or above the melting point of thesodium, which is 97.6° C. With the rise in temperature, the sodiumbecomes molten and reaction with the liquid ensues. Alkali metals havinglower melting points may undergo reaction with the liquid after initialmixing at room temperature.

Oxygen is a necessary reactant in the formation of the decompositionreagent. When air is present, for example, the alkali metal and theliquid react vigorously with the evolution of hydrogen gas. Whenreaction occurs, the reaction mixture takes on a deep amber color. Thiscolor change is distinct and readily observable. Attempts to carry outthe reaction of sodium with polyethylene glycol in an oxygen-freeatmosphere have produced only sodium glycolate and hydrogen. Theresultant solution is virtually clear and is ineffective as adecomposition reagent. However, it has been found that when sodium andpolyethylene glycol are reacted in an atmosphere consisting essentiallyof nitrogen, and oxygen is thereafter introduced into the resultantsodium glycolate solution, the decomposition reagent will be formed, asindicated by the aforementioned color change. Thus, the alkali metal,liquid reactant and oxygen, may be reacted simultaneously, or accordingto the two-step procedure just described. The two-step procedure isadvantageous in that it avoids having hydrogen and oxygen presentsimultaneously in the reaction system, thereby avoiding a potentialexplosion hazard. Furthermore, it lessens the possibility that inactiveby-products will be formed.

Once formed, the decomposition reagent may be used immediately, or itmay be stored for later use. In general, the reagent may be stored forat least six months without significantly diminishing its reactivity.

In order to achieve decomposition of a halogenated organic compound inaccordance with this invention, all that is necessary is to add thecompound to the decomposition reagent in the presence of oxygen and heatthe mixture to obtain a reasonable rate of reaction. It has beendetermined that the use of pure oxygen enhances the rate ofdehalogenation by a factor of five. Efforts to dechlorinate PCBs in aninert atmosphere, such as dry nitrogen, using a decomposition reagentformed from sodium and polyethylene glycol have been unsuccessful. Asfor the extent of heating required for dehalogenation, a temperature ofabout 40° C. to about 180° C. has been found to produce satisfactoryresults. The temperature will vary depending upon the nature of thedecomposition reagent used and the halogenated organic compound beingdecomposed.

Although the reaction mechanism underlying the present invention has notbeen completely elucidated, studies of the decomposition of PCBs using areagent comprising sodium and polyethylene glycol having an averagemolecular weight of 400 have shed some light on the mechanism involved.

As a result of these studies, the following reaction sequence has beenpostulated, in which R signifies the radical --CH₂ --O--CH₂ ]₉ --CH₂ OHand X signifies a PCB residue of the general formula ##STR2## whereina=1 to 5 and b=1 to 5.

A. The reaction of sodium and polyethylene glycol (avg. M.W. 400)proceeds with the formation of a sodium glycolate and the evolution ofhydrogen according to the reaction:

    2 Na+2 R--CH.sub.2 --OH     2 R--CH.sub.2 --ONa+H.sub.2

B. The sodium glycolate disproportionates in a state of equilibrium inaccordance with the reaction: ##STR3##

C. Oxygen insertion between sodium-carbon bonds occurs: ##STR4##

D. The product of the oxygen insertion reaction decomposes into a pairof free radicals: ##STR5##

E. Free radical (I) reacts with free oxygen: ##STR6##

F. The chlorine carbon bonds in PCB's, are attacked by free radical(II): ##STR7##

G. Free radical (III) reacts with additional sodium glycolate: ##STR8##

H. The peroxy derivative produced in the preceding reaction decomposesto form a hydroxylated biphenyl and the sodium salt of a derivative ofglycolic acid. ##STR9##

Consideration had been given the possibility that polyethylene glycolmay undergo the well-known insertion reaction with oxygen to formhydroperoxides in accordance with the following generalized equation:##STR10## This possibility was discounted, however, when it wasdiscovered that this reaction does not readily occur with polyethyleneglycol. When polyethylene glycol is first reacted with sodium, however,as represented in reaction A, the reaction of the sodium glycolate withoxygen occurs readily, as represented in reaction B. It is this reactionthat is believed to produce the aforementioned color change. Thus, itappears that the rapid oxygen uptake that has been observed is due inpart to a reaction that occurs only with polyglycols or polyglycolmonoalkyl ethers by insertion of oxygen between sodium-carbon bonds. Theoxygen of the ether linkages in polyglycols and polyglycol monoalkylethers is believed to give rise to an inductive effect which promotesthe oxygen insertion reaction shown in B.

Solutions resulting from the reaction of sodium with polyethylene glycol(avg. M.W. 400) have been found to give a strong electron spin resonance(E.S.R.) absorption band located at 3,391 gauss, having a narrow bandwidth of 7 gauss. This E.S.R. spectrum matches that observed for thesuperoxide ion, O₂ ⁻. Notwithstanding that the decomposition reagent maycontain such a highly reactive species, the superoxide ion is notbelieved to be the principal reactive species responsible for thedehalogenation of halogen-containing organic compounds that has beenachieved by the method. Such a hypothesis does not account for thecontinuous supply of oxygen required in practice for the decompositionreaction to occur. It has been noted that when the reaction of sodiumand polyethylene glycol is allowed to proceed only to the stage at whichthe superoxide ion is produced, i.e., reaction D, and PCBs are added tothe reaction mixture in the absence of oxygen, no dehalogenation occurs.Dehalogenation has been found to result only when additional oxygen ispresent. This indicates that some species other than the superoxide ionis the active species in the dehalogenation reaction, and has led to theconclusion that the complex sodium glycolate-superoxide radical (II)formed in reaction E, above, is the key species responsible fordehalogenation.

The other free radicals formed in the foregoing sequence, including thesuperoxide ion of reaction D, are believed to be too stable in thereaction medium to have a significant effect on the dehalogenationreaction per se.

From the foregoing reaction sequence, it can be seen that the process ofthe present invention produces relatively innocuous products, theprincipal ones being sodium chloride, and polyhydroxylated aromatics.Hydrogen is also generated as a result of the initial reaction of thealkali metal with the liquid reactant. It should be noted that theformation of sodium chloride in step E above is considered the principaldriving force for the overall reaction sequence.

Polyhydroxylated biphenyls containing as many as eight hydroxyl groupsmay be formed as products of the method described herein. As a class,these polyhydroxylated biphenyls include compounds which are potentiallyuseful as reactants in the production of polymers, as plasticizers, asanti-oxidants, and as solvents for high temperature reactions. Thesecompounds are readily recoverable from the reaction medium byconventional separation techniques, such as solvent extraction.Considering that the useful products formed during the process may bemarketed, at least part of the operating costs of the instant methodshould be recoverable.

Standard safety precautions must be exercised in practicing thisinvention due to the evolution of hydrogen gas which occurs. Thus, theuse of an open flame or exposed electrical heating elements must beavoided. Further, since alkali metals are employed in forming thedecomposition reagent, it is suggested that a safe heating source beused if heating is utilized in preparing the decomposition reagent.Other standard precautions for working with alkali metals must also betaken.

The order in which the steps of the decomposition method are carried outis not considered critical. Thus, while a presently preferred order hasbeen described hereinabove, the method may be practiced otherwise. Forexample, the halogen-containing organic compound may be added to theliquid reactant in the presence of oxygen prior to the addition of thealkali metal. Further, the alkali metal and the halogenated organiccompound may be added simultaneously to the liquid reactant.Alternatively, the alkali metal and halogen-containing organic compoundmay be added to the liquid reactant in an oxygen-free atmosphere, e.g.pure nitrogen, with subsequent introduction of oxygen into the reactionmixture to form the decomposition reagent, whereby completedechlorination of the halogenated compound is rapidly achieved.

The invention will be further understood by reference to the followingexamples.

EXAMPLE I--PREPARATION OF DECOMPOSITION REAGENT AND DECHLORINATION OF APCB OIL (AROCHLOR 1254)

A sodium polyethylene glycol reagent (referred to in these examples asNaPEG) was prepared by placing 900 ml of polyethylene glycol, having anaverage m.w. of 400 (referred to in these examples as PEG 400) in a 3000ml beaker and heating until the temperature approached 80° C. Stirringwas accomplished by using an efficient overhead mechanical stirrer or amagnetic stirring assembly. Thereafter, approximately 55 grams offreshly cut sodium metal was added, all within a two minute period.

CAUTION: If the sodium metal is added over an extended period of timethe possibility of a sodium fire may exist

Within ten minutes, the temperature of the mixture rose to about 120° C.and was maintained as close as possible to this value, until all thesodium, which melted and formed a shiny layer on top of the solvent, hadreacted. Reaction is evidenced by the change of color of the PEG 400 toa dark amber and the disappearance of the shiny metal layer. If all ofthe sodium does not react, small additions of PEG 400 may be used toeffect complete reaction. Alternatively, the NaPEG mixture may be placedin a separatory funnel and the lower NaPEG layer drawn off. Theunreacted sodium metal will rise to the top and may be decomposed byreaction with methanol.

Dechlorination was carried out by heating 25 g of the NaPEG reagentprepared above to 100° C. and adding thereto exactly 10.00 ml of a 1000ppm Inerteen® in cyclohexane standard. Inerteen® is a commercialpolychlorinated biphenyl (PCB) oil manufactured by Westinghouse, Inc. Atthis temperature the cyclohexane boiled off immediately, leaving the PCBin intimate contact with the NaPEG. After 10 minutes reaction time, a 4ml aliquot was withdrawn from the reaction system and then added to 5 mlof distilled water and stirred vigorously for three minutes. Aftercomplete solution of the NaPEG aliquot in water, 5 ml of reagent gradecyclohexane was added to the aqueous system and stirred again for threeminutes.

After the two phases separated, the organic layer was analyzed for itsInerteen concentration via gas chromatography with an electron capturedetector, preceded by a Florosil column clean-up step. The experimentalconditions for the gas chromatographic analysis were as follows:Injection port temperature, 200° C.; Detector temperature, 200° C.;Column temperature, 200° C.; Isothermal scan; Scan time, 20 minutes;Carrier gas, 10% methane in argon; Carrier gas flow rate, 40 ml/minute;Column packing, 1.5% OV-17 and 1.95% QF-1 on 80/100 mesh GasChrom Q.

Gas chromatographic analyses showed the concentration of Inerteenremaining after the ten minute reaction time to be less than 50 partsper billion (ppb).

In all dehalogenation reactions using the NaPEG reagent, a commonreaction product is a sodium halide, which in the case of dechlorinationis specifically sodium chloride. After reaction, a 5 ml aliquot of thereaction medium was added to 50 ml of water and tested for water solubleCl⁻ using a Cl⁻ selective electrode. The analysis showed that the PCBhad been dehalogenated to the extent of 97%±3%.

The Cl⁻ selectivity was tested for possible interferences using aliquotsof fresh NaPEG reagent in water. The Cl⁻ selective electrode wasunresponsive and therefore the NaPEG system itself was free ofinterferences. The rate of appearance of water soluble Cl⁻ may be usedto do precise kinetics measurements on this system.

A confirmatory test for the formation of water soluble Cl⁻ in NaPEGdechlorination reactions was conducted whereby aliquots of the reactionmixtures were acidified with 0.3 M HNO₃, aqeous Ag NO₃ added, and AgClprecipitated. The AgCl residues were analyzed using SEM techniques andfound to be pure.

EXAMPLE II--ALTERNATE PREPARATION OF DECOMPOSITION REAGENT

The NaPEG reagent was also prepared in accordance with the followingtwo-step method. In the first step, 900 ml of PEG 400 and 55 grams ofsodium were placed in a three-neck round bottom flask (2000 ml), whichwas continually flushed with nitrogen gas and heated to a temperature of80° C. Stirring was accomplished by using an efficient overheadmechanical stirrer. A magnetic stirring assembly may also be used. Sincethere is no oxygen present in the reaction vessel, the possibility of asodium fire is greatly reduced when following this procedure. Hydrogenwas evolved as a result of the reaction between the dissolved sodium andthe PEG 400. At this point, the reaction mixture was essentiallycolorless. No reaction was observed when a PCB oil was added to thereaction mixture. When air was introduced into the reaction mixture, arapid reaction occurred as evidenced by the color change to dark amberdescribed in Example I, thus indicating that the NaPEG reagent had beenformed.

EXAMPLE III--DECHLORINATION OF PCB'S IN HYDROCARBON-BASED TRANSFORMEROILS

The NaPEG reagent was prepared in the same manner as set forth inExample I. One quart of hydrocarbon-based transformer oil, contaminatedwith approximately 1000 ppm of PCB's, was heated to 100° C. in a twoliter beaker. Thereafter, 25 grams of NaPEG reagent were added to theoil sample and stirred vigorously, using an overhead mechanical stirreror a magnetic stirring assembly.

After 1 hour reaction time, the reaction mixture was allowed to cool toroom temperature and then was added to a 4000 ml separatory funnelequipped with either a glass or Teflon stopcock. To help ensure completetransfer of the oil sample, small (25 ml or less) portions of a 1 N NaOHsolution may be used to rinse the beaker. To extract products of thedechlorination reaction, 1 liter of 1 N NaOH was added to the separatoryfunnel which was then stoppered and shaken vigorously for five minutes,venting excess pressure buildup as necessary. The aqueous layer wasdrawn off and discarded and the extraction procedure with NaOH wasrepeated with a fresh 1 liter sample of aqueous base. Extractions wererepeated until the aqueous layer showed no visible dark coloration afterextraction. This will generally require 3-5 extractions with fresh NaOHsolution.

After disposal of all aqueous extracts, the transformer oil, which isusually turbid, was dried and clarified by passing through a column of 5Angstrom molecular sieves. The molecular sieves were packed in a glasstube fitted with a stopcock or other means of regulating eluant flowrate. The dimensions of the glass column were approximately 1 inchinside diameter by 19 inches in length. The column was prepared byplacing a small wad of glass wool in the bottom of the tube and thenplacing a 14 inch bed of molecular sieves atop the glass wool. The oilsample was dried by simply pouring it through the column and collectingthe eluant in a clean, dry flask. The rate of elution should not exceed2 drops per second, or the sample will not be effectively dried. Inaddition, the first 50-75 ml of eluant will have to be re-added to thesystem to complete the drying procedure, because the initial amount ofoil added to the column will pass through very quickly and will not beefficiently contacted by the molecular sieves.

The concentration of PCBs remaining in the dried transformer oil wasdetermined by removing a 10 ml sample of oil, adding it to an equalvolume of pure PEG 400, and stirring vigorously for three minutes. ThePCBs were extracted into the PEG 400 layer and were further extracted byremoving the PEG 400 layer and adding it to 10 ml of reagent gradecyclohexane. After stirring vigorously for five minutes, the two layerswere allowed to separate and the cyclohexane layer was analyzed by gaschromatography as described in Example I. The results showed residualPCB to be present in a concentration of less than 50 ppb.

This example shows that the method of this invention may be usedeffectively to scavenge PCBs from recyclable materials contaminatedtherewith.

EXAMPLE IV--DECHLORINATION OF "NEAT" PYRANOL (AROCHLOR 1248) USING NaPEGREAGENT

Pyranol, another type of commercial PCB oil, was dechlorinated in amanner essentially identical to that described in Example I. For everygram of pyranol dechlorinated, approximately 5 grams of NaPEG reagentwere required. The pyranol in this case was added neat, i.e., notdiluted in an organic solvent. Preparation of the NaPEG reagent,dechlorination procedure, and post-reaction analyses were carried out ina manner identical to those described in Example I. The analyses showedthat the chlorine content of the pyranol had been reduced by about97%±3%.

EXAMPLE V--DECHLORINATION OF PURE HEXACHLOROBENZENE USING NaPEG REAGENT

Hexachlorobenzene was dechlorinated in a procedure essentially identicalto that described in Example I. The only exceptions were thathexachlorobenzene was added neat and that the weight ratio was fourgrams of NaPEG reagent per gram of hexachlorobenzene dechlorinated. Gaschromatographic analyses showed the hexachlorobenzene to be essentiallycompletely dechlorinated, with residual concentrations of 50 ppb orless.

EXAMPLE VI--DECHLORINATION OR TRICHLOROBENZENE ISOMERS USING NaPEGREAGENT

The various isomeric trichlorobenzenes were investigated because theycan make up as much as 50% of the composition of industrial PCB oils.They have been dechlorinated in a manner essentially identical to thatdescribed in Example I. The only differences were that thetrichlorobenzenes were added to the reagent neat and that approximatelythree grams of NaPEG were required for each gram of trichlorobenzenedechlorinated. In the gas chromatographic analyses, the scan time forthe chromatogram can be reduced to approximately five minutes, owing tothe low polarity and molecular weights of the isomerictrichlorobenzenes. Analysis, using a Cl⁻ selective electrode showed thatthe chlorine content of the trichloroenzenes had been reduced by about97%.±3%.

EXAMPLE VII--DECHLORINATION OR HEXACHLOROCYCLOHEXANE USING NaPEG REAGENT

Pure hexachlorocyclohexane was dechlorinated using the procedures ofExample I. 10 mls of a 1000 ppm solution of hexachlorocyclohexane incyclohexane was added to the NaPEG reagent. Analysis of using a Cl⁻selective electrode showed that the chlorine content of thehexachlorocyclohexane had been reduced by about 97%.

EXAMPLE VIII--DECHLORINATION OF KEPONE USING NaPEG REAGENT

Kepone® was dechlorinated using the procedures of Example 1. Kepone® wasdissolved in a 15% (by vol) acetone-cyclohexane mixture to the extent of1000 ppm. 10 ml of this solution was added to the NaPEG reagent. Gaschromatographic analyses showed the Kepone to be substantiallycompletely dechlorinated.

EXAMPLE IX--DECOMPOSITION OF CHLOROETHYLETHYLSULFIDE USING NaPEG REAGENT

The procedures of Example 1 were applied to 5 ml of neatchloroethylethylsulfide (a "Mustard gas" model compound). The compoundwas completely dechlorinated, and the carbon-sulfur bond cleaved. Thereaction products were determined to be NaCl, Na₂ S, and ethanol.

EXAMPLE X--DECHLORINATION OF DDT USING NaPEG REAGENT

DDT, dichlorodiphenyltrichlorethane, was treated using the procedures ofExample 1. 10 ml of a 1000 ppm cyclohexane solution of DDT incyclohexane was added to the NaPEG reagent and complete dechlorinationoccurred in less than 10 minutes, as determined by gaschromatography/electron capture techniques.

Procedures similar to those set forth above have been followed for thedehalogenation of tetrachlorobenzene and pentachlorophenol.

Although the method of the present invention has been exemplified withreference to the decomposition of specific halogenated organiccompounds, the process may be used with success for the decomposition ofa wide variety of other halogen-containing organic compounds. Mixturesof organic halogenated compounds other than PCBs may also be decomposedby this method.

Those skilled in the art will appreciate that the method disclosed inthe foregoing examples is merely illustrative and is capable of widevariation and modification without departing from the scope of theinvention as defined in the appended claims.

We claim:
 1. A method for the decomposition of a halogenated organic compound, comprising the steps of:(a) providing a reaction mixture comprising the halogenated compound, a reactant having the general formula ##STR11## wherein R is hydrogen or lower alkyl, R₁ and R₂ are the same or different and are selected from the group consisting of hydrogen, unsubstituted or substituted lower alkyl, unsubstituted or substituted cycloalkyl having from 5 to 8 carbon atoms, and unsubstituted or substituted aryl, n has a value of from 2 to about 400, and x has a value of at least 2, and an alkali metal; and (b) reacting said reactant with said alkali metal and oxygen to form a decomposition reagent, which effects substantially complete removal of halogen from said halogenated compound and forms an oxygenated derivative of said compound.
 2. The method claimed in claim 1 wherein the alkali metal is selected from the group consisting of sodium, potassium, and amalgams thereof, and R¹ and R² in the general formula are hydrogen, x is 2, and n has a value between 3 and
 440. 3. The method claimed in claim 2 wherein the halogenated organic compound is selected from the group consisting of hexachlorocyclohexane, hexachlorobenzene, trichlorobenzene, tetrachlorobenzene, pentachlorophenol, dichlorodiphenyltrichloroethane, decachlorooctahydro-1,3,4-mehteno-2H-cyclobuta-pentalen-2-one and polychlorinated biphenyl.
 4. A method for the decomposition of a halogenated organic compound, comprising the steps of:(a) providing a reaction mixture comprising the halogenated compound, a reactant having the general formula ##STR12## wherein R is hydrogen or lower alkyl, R₁ and R₂ are the same or different and are selected from the group consisting of hydrogen, unsubstituted or substituted lower alkyl, unsubstituted or substituted cycloalkyl having from 5 to 8 carbon atoms, and unsubstituted or substituted aryl, n has a value of from 2 to about 400, and x has a value of at least 2, and an alkali metal; (b) reacting said reactant with said alkali metal in a substantially oxygen-free atmosphere to produce an intermediate product; and (c) reacting oxygen with the intermediate product produced in step b to form a decomposition reagent which effects substantially complete removal of halogen from said halogenated compound and forms an oxygenated derivative of said compound.
 5. The method claimed in claim 4 wherein the substantially oxygen-free atmosphere consists essentially of nitrogen.
 6. The method claimed in claim 4 wherein the alkali metal is selected from the group consisting of sodium, potassium, and amalgams thereof, and R¹ and R² in the general formula are hydrogen, x is 2, and n has a value between 3 and
 400. 7. The method claimed in claim 6 wherein the halogenated organic compound is selected from the group consisting of hexachlorocyclohexane, hexachlorobenzene, trichlorobenzene, tetrachlorobenzene, pentachlorophenol, dichlorodiphenyltrichloroethane, decachlorooctahydro-1,3,4-metheno-2H-cyclobuta-pentalen-2-one and polychlorinated biphenyl.
 8. A method for the decomposition of a halogenated organic compound, comprising the steps of:(a) providing a decomposition reagent formed by reacting an alkali metal, a reactant having the general formula: ##STR13## wherein R is hydrogen or lower alkyl, R₁ and R₂ are the same or different and are selected from the group consisting of hydrogen, unsubstituted or substituted lower alkyl, unsubstituted or substituted cycloalkyl having from 5 to 8 carbon atoms, and unsubstituted or substituted aryl, n has a value from about 2 to about 400 and x has a value of at least 2, and oxygen; and (b) reacting said decomposition reagent with said halogenated organic compound in the presence of oxygen to effect substantially complete dehalogenation of said halogenated organic compound and form an oxygenated derivative of said compound.
 9. The method claimed in claim 8 wherein said decomposition reagent is produced from an alkali metal selected from the group consisting of sodium, potassium, and amalgams thereof, and a liquid reactant of the above general formula wherein R¹ and R² are hydrogen, x is 2, and n has a value between 3 and
 400. 10. The method claimed in claim 9 wherein the halogenated organic compound is selected from the group consisting of hexachlorocyclohexane, hexachlorobenzene, trichlorobenzene, tetrachlorobenzene, pentachlorophenol, dichlorodiphenyltrichloroethane, decachlorooctahydro-1,3,4-metheno-2H-cyclobuta-pentalen-2-one and polychlorinated biphenyl.
 11. A method for the decomposition of a polychlorinated biphenyl, comprising the steps of:(a) providing a decomposition reagent formed by reacting an alkali metal, a reactant having the general formula: ##STR14## wherein R is hydrogen or lower alkyl, R₁ and R₂ are the same or different and are selected from the group consisting of hydrogen, unsubstituted or substituted lower alkyl, unsubstituted or substituted cycloalkyl having from 5 to 8 carbon atoms, and unsubstituted or substituted aryl, n has a value from about 2 to about 400 and x has a value of at least 2, and oxygen; and (b) reacting said decomposition reagent with said polychlorinated biphenyl in the presence of oxygen to effect substantially complete dehalogenation of said halogenated organic compound and form an oxygenated derivative of said compound.
 12. The method claimed in claim 11 wherein said decomposition reagent is produced from sodium and polyethylene glycol.
 13. A method for the decomposition of a polychlorinated biphenyl, comprising the steps of:(a) providing a reaction mixture comprising the polychlorinated biphenyl, a reactant having the general formula ##STR15## wherein R is hydrogen or lower alkyl, R₁ and R₂ are the same or different and are selected from the group consisting of hydrogen, unsubstituted or substituted lower alkyl, unsubstituted or substituted cycloalkyl having from 5 to 8 carbon atoms, and unsubstituted or substituted aryl, n has a value of from 2 to about 400, and x has a value of at least 2, and an alkali metal; and (b) reacting said reactant with said alkali metal and oxygen to form a decomposition reagent which effects substantially complete removal of halogen from said polychlorinated biphenyl and forms an oxygenated derivative of said compound.
 14. The method claimed in claim 13 wherein the alkali metal is sodium and the liquid is polyethylene glycol.
 15. A method for the decomposition of a polychlorinated biphenyl, comprising the steps of:(a) providing a reaction mixture comprising the polychlorinated biphenyl, a reactant having the general formula ##STR16## wherein r is hydrogen or lower alkyl, R₁ and R₂ are the same or different and are selected from the group consisting of hydrogen, unsubstituted or substituted lower alkyl, unsubstituted or substituted cycloalkyl having from 5 to 8 carbon atoms, and unsubstituted or substituted aryl, n has a value of from 2 to about 400, and x has a value of at least 2, and an alkali metal; (b) reacting said reactant with said alkali metal in a substantially oxygen-free atmosphere to produce an intermediate product; and (c) reacting oxygen with the intermediate product produced in step b to form a decomposition reagent which effects substantially complete removal of halogen from said polychlorinated biphenyl and forms an oxygenated derivative of said compound.
 16. The method claimed in claim 15 wherein the alkali metal sodium and the liquid is polyethylene glycol.
 17. A method for the decomposition of a chlorinated organic compound comprising the steps of:(a) reacting sodium, polyethylene glycol and oxygen at a temperature of from about 80° C. to about 120° C. to form a decomposition reagent; and (b) adding the chlorinated compound to the decomposition reagent in the presence of oxygen and heating to about 100° C. to effect substantially complete dechlorination of the chlorinated compound and form an oxygenated derivative of said compound.
 18. A method for the decomposition of a chlorinated organic compond comprising the steps of:(a) mixing the chlorinated compound with polyethylene glycol; (b) reacting the polyethylene glycol with sodium in a substantially oxygen-free atmosphere at a temperature of from about 80° C. to about 120° C.; and (c) reacting oxygen with the reaction products of step b and heating the reaction mixture to about 100° C. to effect substantially complete dechlorination of the chlorinated compound and form an oxygenated derivative of said compound.
 19. The method claimed in claim 18 wherein the substantially oxygen-free atmosphere consists essentially of nitrogen.
 20. The method claimed in claim 15 wherein the substantially oxygen-free atmosphere consists essentially of nitrogen.
 21. A method for the decomposition of a polychlorinated biphenyl, comprising the steps of:(a) reacting sodium, polyethylene glycol and oxygen at a temperature of from about 80° C. to about 120° C. to form a decomposition reagent; and (b) adding the polychlorinated biphenyl to the decomposition reagent in the presence of oxygen and heating to about 100° C. to effect substantially complete dechlorination of the polychlorinated biphenyl and form an oxygenated derivative thereof.
 22. A method for the decomposition of a polychlorinated biphenyl comprising the steps of:(a) providing a reaction mixture comprising the polychlorinated biphenyl, polyethylene glycol and sodium; (b) reacting said polyethylene glycol with said sodium in a substantially oxygen-free atmosphere at a temperature of from about 80° C. to about 120° C.; and (c) reacting oxygen with the reaction products of step b and heating the reaction mixture to about 100° C. to effect substantially complete dechlorination of the polychlorinated biphenyl and form an oxygenated derivative thereof.
 23. The method claimed in claim 22 wherein the substantially oxygen-free atmosphere consists essentially of nitrogen. 